The present invention relates to setting an annular seal. In particular the present invention relates to a device for setting an annular seal in a well that is used for recovering fluids from an underground formation or for storing fluids in an underground formation.
Wells used for recovering fluids from underground formations are typically boreholes that are lined with well tubulars in the form of a casing string or a liner. In particular for deep wells, the borehole is drilled in stages, wherein each stage is lined with a casing string that is lowered into the borehole, and wherein the inner diameter of the hole of each next stage is smaller than the inner diameter of the preceding stage(s). Consequently the casing string for a next stage has an outer diameter that is smaller than the inner diameter of the preceding stage(s).
The annular space between two tubulars is called the annular clearance, and the skilled person is able to select the annular clearance that is required under the circumstances in order that the next tubular can be lowered through the preceding tubular(s).
The annular space between the outer surface of a casing string and the inner surface of the borehole is normally filled with cement. The cement can be placed along the entire length of the casing or only along the lower part of the casing.
In order to prevent leakage, the upper end of a next tubular (having a smaller outer diameter) is hung-off in the lower end of the previous tubular (having a larger inner diameter), so that an overlap section is formed. An annular seal is set in the overlap section.
It is an object of the present invention to provide a device for setting the annular seal.
In accordance with the invention there is provided a device for setting an annular seal in an annular space formed between a large diameter tubular and a small diameter tubular extending into the large diameter tubular, the device comprising a carrier block suitable to be located at a position in the large diameter tubular proximate said annular space, the carrier block being provided with a carrier ring axially movable relative to the carrier block between a first position and a second position and arranged to axially move the annular seal into the annular space upon movement of the carrier ring from the first to the second position thereof, and further comprising an explosive charge arranged to move the carrier ring from the first position to the second position thereof and detonator means for selectively detonating the explosive charge.